A senior Auckland unionist says the proposed "living wage" of $18.40 an hour is not enough in Auckland.

Service and Food Workers Union lead organiser Len Richards told a conference launching the living wage at AUT University yesterday that Aucklanders needed $24 an hour to pay higher rents and other costs.

But Lower Hutt-based Anglican Family Centre researchers Reverend Charles Waldegrave and Peter King, who calculated the $18.40 rate as the minimum required to "live with dignity" in New Zealand, said it was impossible to take account of all workers' different circumstances.

"If you have five children, that's a huge difference too," Mr Waldegrave said.

The researchers attracted mostly friendly questions from an audience made up largely of the union and community groups that are backing the campaign for a living wage.

They acknowledged that the living wage would have been $24.11 an hour in Auckland if they had used the lower-quartile rent for a three-bedroom house in Auckland of $438 a week instead of the national average of $275.

But they argued in their report that it was clearer to set a national living wage and ask the Government to increase the accommodation supplement to cover Auckland's higher rents.

Mr Richards said that approach would not work.

"If you raised the accommodation supplement in Auckland, the rents would go up. It's a landlord's subsidy," he said. "I think the best way to address that situation is actually to have an Auckland living wage rate, because it's clear that Auckland costs are so much higher."

London's living wage of £8.55 ($15.62) an hour, endorsed by mayor Boris Johnson, is 15 per cent higher than the £7.45 ($13.61) set for the rest of Britain.

However, Auckland's $24.11 is not only 30 per cent higher than the proposed $18.40 national living wage, but is higher too than the national median wage of $20.86 an hour, so it would mean seeking higher wages for the lowest-paid Aucklanders than for more than half of all workers.

Waikato University labour economist Dr Bill Cochrane said median three-bedroom house rents varied hugely within Auckland, from just under $400 a week in the poorest areas up to around $750.

"Your basic problem is the affordability of housing. People can't afford the housing that there is because there is a lack of adequate affordable housing," he said. "The emphasis should be on the provision of public housing."

Council of Trade Unions economist Dr Bill Rosenberg said the Government should also consider different rates of benefits and tax credits for Auckland.

Officials reviewing the accommodation supplement and state house rental policies were due to report in December, and new Housing Minister Nick Smith is likely to be considering their recommendations now.